Laboratory information management systems are known generally. Some such systems permit the operator to select a rule against which one or a group of such results may be tested. Typically, the way in which this is done is that control solutions having known concentrations of a medically significant component of interest, for example, a hormone, are processed by the laboratory instrument right along with patient samples. The programmable machine then tests the laboratory instrument's concentration determination results against the known concentrations of the hormone in the various controls as determined by the laboratory instrument.
The statistical quality control test, or rule, might be, for example, "Is the reported result for the control solution within one standard deviation of the known concentration?" If the answer to such a test is "Yes," the laboratory instrument's concentration determination process is considered to be in control, and testing to determine the concentration of the hormone in patient samples proceeds. If the answer to this question is "No," the laboratory instrument's concentration determination process is considered to be out of control, and appropriate steps are taken to bring the process back into control and/or to retest the affected patient sample concentration determinations to provide more reliable results.
There are various sources of statistical quality control rules. Examples of collections of such rules are the so-called Rilibak rules and the Westgard rules, attributed to Dr. James O. Westgard. Westgard statistical quality control has been implemented manually in the control of processes using Shewhart charts. These statistical quality control strategies, while effective, permitted only off-line, non-real time testing of process results against the statistical quality control rules. What this ordinarily meant in the manufacturing context, for example, is that by the time statisticians became aware that a manufacturing process was out of control, several potentially non-conforming units of manufacture had already been produced. This, of course, typically dictated that further quality checking be performed on suspected non-conforming units of manufacture, and/or corrective action be taken as necessary.